This study concerns the inhibition of the corrosion of the aluminium alloy 3003 in a solution of 3% NaCl by Li+, Mg2+, MoO42-, NO2- and CrO42- ions. The methods used are the determination of the polarization curves and the metallographic examination of the surface condition. The results obtained show that the tested ions inhibit the corrosion process.The comparative study of the effect of these ions shows that the Mg2+ ions are the most efficient ones in the temperature range from 25 to 65°C. The inhibition efficiency increases with the concentration of these ions and reaches a maximum value of 86% for 5 × 10-2 alloy. As a consequence, the gap between pitting and corrosion potentials becomes larger. At 75°C, Mg2+ ions tend to stimulate corrosion of alloy 3003 in the chloride solution considered.

Steel velocity measurement in the mould has been carried out using a Karman vortex flowmeter. The sensor is based on Karman vortex streets, which occur when a flowing fluid encounters a fixed body. A linear relation exists between the velocity of the fluid flow and the shedding frequency of Karman's vortices, therefore by measuring the frequency, the velocity of the fluid flow can be calculated. The system consists of two consumable sensor rods, which are placed at either side of the SEN. With the end plates instrumented with additional thermocouples, it is possible to relate the differential velocity measurement to end plate temperatures.

In the last few years, CPM developed a first generation of charging model for coke ovens to improve the uniformity of oven filling and to reduce charging emissions. A new charging model has been recently built to simulate all kinds of charging process with 3, 4 or 5 charging holes and to obtain a more reliable representation of the levelling operation. More particularly, coal accumulation in each compartment of the leveller bar is represented, in order to have a better idea of the gas free space during the levelling operation. By using this model, it is now possible to suppress or reduce coal accumulation in the oven free space during the levelling operation and to obtain a constant and uniform coal profile at the end of charging, without gas emissions.

Physical model experiments were performed to clarify the influence of orifice configuration on the volumetric mass transfer coefficient during ladle purging. Bubble behavior was recorded by a high speed video camera in the present study. And carbon dioxide desorption from an aqueous NaOH solution was used to measure the volumetric mass transfer coefficient. It is found that bubbles for multi-hole orifice are generally smaller than those for 1-hole orifice. However, when the hole distance in the multi-hole orifice is too short to avoid bubble coalescence, large bubbles will be formed. It is shown that there is a decreasing tendency of the volumetric mass transfer coefficient when the hole diameter increases. The volumetric mass transfer coefficient firstly increases with increasing the hole distance and hole number. Thereafter, it remains approximately constant with further increase in the hole distance and hole number.

Data from the Rautaruukki Raahe sinter plant were analyzed with feed-forward neural networks. The resulting models were used to investigate and optimize the sinter plant production rate and the reduction degradation index (RDI) that is an important sinter quality indicator for small blast furnaces. Especially, the effects of controllable parameters such as the chemical composition of sinter, physical conditions of raw materials and factors reflecting the sintering event were studied.

Based on the balance equations of mass, partial mass,momentum and thermal energy, the pyrolysis processof non-coking coals using a counter-rotating twin screwreactor (TSR) is modelled by means of commercial CFDcode PhoenicsTM. In favour of good convergence of themathematical solution, a structured, cylindrical-polar gridis chosen. Variable filling and intermeshing degrees aretaken into account by blocking numerical cells in gasdomain and intermeshing domain instead of performingtwo-phase calculations in a body-fitted co-ordinate system.Viscous behaviour of the granular coals is expressed bymeans of a generalised Newtonian fluid and chemicaldecomposition is implemented with aid of distributedactivation energies.

In horizontal continuous casting or in meniscus free continuous casting, the appearance of corrugations or marks at the surface of the cast products cannot be related with the partial solidification of the meniscus of the free surface of the liquid metal, like in the case of the classical vertical continuous casting process. In order to find their origin, an experimental work has been carried on with two different experimental devices. The first one provides solidified metallic samples to be observed and analysed. With the other one, it is possible to directly look at the formation of the skin on the mould during the solidification of transparent organic compounds. Here, we firstly present the results of the observation of the surface of samples cast in very different casting conditions. In a companion paper, we propose a description of the formation of the marks and corrugations in terms of basic phenomena which occur during solidification.

Improvements have been made to slab, bloom, billet and thin slab caster secondary cooling systems giving better control of strand surface temperature and quality. This has been achieved by a combination of laboratory-based tests of spray characteristics and heat transfer coefficient (htc), innovative mathematical modelling and detailed on-plant measurements of temperatures and spray conditions.

The efficiency of automatic flatness control systems in tandem cold mills is mainly based on the accuracy of the prediction models and on the selection of optimum control concepts. BFI, together with EKO Stahl, has recently developed and partly applied advanced flatness control strategies (providing online-adaptation of actuator action to thickness profile information and in-gap process condition towards a fully integrated flatness control of all stands) that are superior to conventional techniques and lead to significant improvements in strip flatness. The present article aims to demonstrate the principles, advantages and results of this work.

The German metal industry is confronted with an enforcing international competition,rising prices of energy and commodities, the increasing relevance of sustainable economy,political demands and incentives such as emission trading. To meet these challenges it isessential for companies to further improve resource and energy efficiency and to reduceCO2 emissions. Usually, efforts concerning these objectives focus on new orimproved single processes. In contrast, the presented approach extends the considerationsto the inter-company perspective and considers multiple processes from ferrous andnon-ferrous metals industry which are linked by material flows. Our considerations focuson residue flows in the iron and steel as well as the zinc industry. Steel production inintegrated steelworks or electric steel plants involves the formation of large amounts ofby-products, e.g. dusts, sludges or slags. These contain valuable substances such as ironor zinc and can be further processed by internal re-feeding or external recycling, e.g. byspecialized companies, particularly Waelz kiln plants or the DK process. The latterproduce zinc concentrates for the zinc industry. Changes in the modes of operation of oneor more process can therefore affect the connected processes. We investigate strategies tofurther reduce landfilling and to efficiently allocate by-products to internal andexternal recycling options within the scope of the sketched network. We develop flowsheetmodels for representative processes within the regarded industries in Germany. With anElectric Arc Furnace (EAF), an integrated steelworks, two recycling companies, and ahydrometallurgical zinc plant the major processes of the German iron, steel and zincindustries are considered. We derive linear input-output functions for each of theprocesses by means of multiple linear regression analysis which we apply on results ofsystematically varied flowsheet simulation runs. These functions are used in a system oflinear equations, forming a material and energy flow model of the regarded network. Themodel is applied to identify and assess strategies and measures to enhance resource andenergy efficiency and to reduce climate relevant CO2 emissions by scenario andsensitivity analyses. Thus, technical and economical barriers of inter-company measurescan be overcome by identifying strategies which are technologically feasible and favorablewith regard to the named objectives.

Hot rolling and solution annealing of duplex stainless steels involve high temperature reheating steps in oxidizing atmospheres. The thin scale that forms on the surface is not easily removed because it contains oxide nodules that are deeply embedded in the underlying alloy. These nodules appear when the protective Cr2O3 layer becomes locally inefficient. At the same place, oxidation of iron and manganese is possible and less chromium is needed to develop the scale. Depletion of chromium in the steel beneath the nodule is then less important and pickling the plates becomes more difficult.

The attachment mechanism of inclusions to bubbles hasbeen studied with water model experiments under turbulentcondition. Change in particle-number concentration indicatesthat the removal rate follows first order kinetics. It increaseswith particle diameters and particle contact angles.

LABEIN and ACB have developed a model to predict the mechanicalproperties of the hot rolled products, considering as a first stepthe hot rolling of thin slabs on the 7 stands hot strip mill (thin slabdirect rolling) of the Sestao steelworks.
The thermomechanical model includes a thermal module and adeformation module. It is supplemented with a microstructuralmodule and a mechanical properties module. The model has beenvalidated versus industrial results. It also includes an optimizingmodule that makes it possible to define the most appropriate processevolutions to meet new product requirements.

The development of steel refining operations at ArcelorMittalFCWE for the production of ULS steels is reported. Several plants with different equipments produce grades with S <30 ppm, thus permitting to identify the most efficient process, from hot metal desulfurization to secondary metallurgy. For sites producing steels with S <30 ppm, four secondary metallurgy routes coexist in ArcelorMittal FCWE. The Vacuum Tank Degasser makes it possible to reach very low S and N contents simultaneously. To face the increase of the share of Ultra Low Sulfur products, it is necessary to further enhance the kinetics of desulfurization by steel - slag stirring at the atmospheric pressure.

VAI-Q Strip is a quality control system, based on physical-metallurgical models, for hot-rolled strip. This joint development of VOEST-ALPINE Industrieanlagenbau and VOEST-ALPINE Stahl Linz allows the automatic on-line control of the mechanical properties using very accurate prediction methods. Since the beginning of 2000, an extended version of the system is in operation at VOEST-ALPINE Stahl Linz and very good quality results, as well as cost savings, have been achieved.

Examples of high cycle thermal fatigue (HCTF) damage cases onPWR austenitic stainless steel components are reported. High cyclethermal fatigue risk is primarily due to mixing of cold and hot water,unexpected leaks of cold water through check valves or to turbulentpenetration of hot water running in a main pipe into a connected line.When such thermal fatigue issues are identified in PWR powerplants, manufacturing improvement such as inner surface polishingof austenitic stainless steel parts can be performed to increase thefatigue resistance of the components.

The recent projects and the new EAF orders indicate a newtrend in the furnace design proposing very big electric arcfurnaces. Concast, after the first successful installation in2003 of the 180 t EAF in Icdas, wants to reproduce the reallyoutstanding performances of this EAF with the new 220 tEAF producing 320 t/h. The equipment installed and thefurnace design will follow the “Ultra High Chemical Power”EAF indexes.
An analysis on the basic engineering parameters and theextrapolation of its performance are presented.

Simulation experiments were conducted to identify the dominant factors that affect topdross generation in metal coating baths. From the experiments and the microstructuralanalyses of the top dross, it is proposed that top dross is generated through bath metalentrainment by the oxide film and subsequent drainage during holding. A new concept,taking into consideration the fresh area creation during the wiping process, is introducedand a mathematical model is developed to quantify dross generation in the metal coatingprocess. From the proposed mechanism, a new metric is developed to quantify top drossgeneration in the coating bath. The experimental results agree well with both theoreticalresults and production data of galvanising (GI) baths based on this metric.

The Production of aluminium is one of such industrial processes that have the potential to release great quantities of dangerous toxic material into the atmosphere. To protect the environment, the Alucam Company has put in place two collection and treatment stations. The main indicator of performance of this system is the collection and treatment efficiency. All other parameters kept constant, this efficiency is proportional to the fume flow rate at the chimney. But the key parameters to control in case of variation are poorly mastered. The collection efficiency of the treatment stations can deteriorate at any moment without any successful intervention to bring back the situation to normal. This article presents the first part of a research work which intends to solve this problem of variations in the flow rate by increasing the fume flow rate and controlling the system within specified limits. We use a Continuous Improvement Methodology which involves the use of Six Sigma tools at the completion of the analysis phase of which we get the fundamental causes of the low performance.

Hot tearing defects appear during the last steps of casting solidification of dendrites.The crystalline structure traps a small amount of liquid metal, which is depressed, andcavities are spontaneously initiated. Molecular dynamics (MD) simulations of pure iron areable to predict, on one hand, the high temperature elastic modulus of crystals, and on theother hand, the cavitation event in liquid metal and near the solid-liquid growth front.High values of elastic tensor components are predicted close to the melting temperature.We conclude that a weakening of the mechanical properties of the crystal is not the reasonfor failure initiation. The crystals are thinned by partial melting as the effect ofnegative pressure increases. The cavitation is spontaneously initiated under a very highnegative pressure. The cavity expands very quickly and applies a pressure wave to thethinned crystals. We propose that this crystal thinning/pressure wave coupling is able toinitiate cracks inside the crystal.